textproduct: Quad Cities

KEY MESSAGES

- Patchy fog early this morning, mainly confined to river valleys and nearby areas. - Hot and humid conditions persist into the weekend with highs around 90 to near 95 and heat indices in the 90s to around 100F. A Heat Advisory remains in effect for portions of NE Iowa and NW Illinois this afternoon.

- Wildfire smoke will be around in our skies into the weekend, making for hazy sunshine and vibrant sunrises and sunsets. The smoke is likely to remain mostly aloft, and could be dense enough at times to limit high temperatures by a few degrees. - Shower and storm chances gradually increase for the end of the week and beginning of the weekend.

- Pattern change next week will bring periodic storm chances and cooler temperatures.

SHORT TERM /THROUGH TONIGHT/

Issued at 250 AM CDT Wed Jul 15 2026

Early this morning, all is tranquil beneath high pressure with mainly clear skies and light winds. The added low level moisture and radiational cooling is supporting river valley fog once again, which may be dense in some locations though not likely to see widespread dense fog.

The region remains beneath an elongated and anomalous mid-upper level ridge extending from the Northern Plains to the Mid- Atlantic. At the surface, the high center will shift a bit into western Iowa. This will lead to the development of a predominantly northerly wind today, albeit light to where it likely won't have too much of an impact in sensible weather with it remaining very warm/hot and humid. What could have an impact on temperatures some today is wildfire smoke, which arrived in our skies yesterday sliding southeastward through the Great Lakes and then advecting westward around the periphery of the upper high centered over southern MN last evening. Last few GOES East CIRA Geocolor images late yesterday afternoon showed a plume of fairly dense smoke aloft over IN/ OH sliding westward seemingly toward our region. The latest HRRR vertically integrated smoke product appears to have caught more onto this greater concentration and is suggesting higher smoke concentrations working into the region today, especially from around I-80 northward and along/east of the Mississippi River. If this occurs, highs (lower 90s) today could end up being a few degrees cooler than forecast particularly in the areas that see greater upper level smoke concentration. Areas in IN/OH beneath the thicker smoke yesterday saw temperatures in the range of 86 to 90F. Given the potential impacts to temperatures from the smoke, I don't have the confidence to make any changes to the Heat Advisory, which remains in effect this afternoon for parts of NE Iowa and NW Illinois north of U.S. Hwy 30. If the smoke is thinner and not as impactful on temps then there is the potential for several hours of 100+ degree heat index readings, and not only in the advisory area but also potentially further southward toward I-80. Will have to keep an eye on satellite today and adjust temperatures and headlines where/if needed.

Tonight, mainly clear skies and light winds combined with the low level moisture may once again lead to fog in valleys and nearby areas. A weak backdoor front/wind shift from Lake Michigan may reside from southern WI into parts of N IL, mainly just outside our service area along with any clouds and very low (15%) chances for a shower. Lows look to be in the upper 60s to near 75F.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 250 AM CDT Wed Jul 15 2026

Hot and humid conditions look to persist into the weekend with highs around 90 to near 95F and heat index readings from the mid 90s to around 100F. There remains uncertainty with highs continuing into the weekend due to the potential for Canadian wildfire smoke, as an upper jet extends across the Upper Midwest and Great Lakes.

Increasing moisture with some Gulf input along with initially a weak backdoor front in the vicinity of N IL and a weakening upper low lifting northward toward the region will lead to shower and storm chances mainly Thursday PM and Friday PM. The greater coverage (possibly 50-70%) will be favored Friday afternoon into evening south/east of the QC metro being in closer proximity to the better forcing from the weakening upper low. While we'll have ample CAPE both days, very weak shear should keep any storms that develop disorganized and short- lived. Primary risk with these storms will be gusty winds (low risk for isolated severe) with precip loading and as cell collapse. Slow motions will lead to the potential for localized heavy downpours potentially 1"+.

The pattern is set to undergo a change toward broad eastern troughing and western ridging over the weekend into next week. A series of shortwaves or ridge riders on the edge of the "ring of fire" out west should result in periodic storm chances. Can't rule out some severe threat at times in the northwest flow aloft, but plenty of uncertainties in timing/strength/ location of these waves at this range. What is of higher confidence is a return to cooler/seasonable temperatures next week with the Climate Prediction Center (CPC) latest 6-10/ 8-14 day outlooks showing some signal (30-40%) for leaning below normal July 20-28. We may see some signs of this transition toward more seasonable conditions as early as Sunday, particularly across our north/east counties as surface ridging temporarily builds down through the Great Lakes.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 555 AM CDT Wed Jul 15 2026

Early morning satellite shows areas of fog lurking in many river valleys, which earlier overnight led to a brief period of VLIFR visibility at DBQ. Based on satellite, DBQ and BRL would appear to have the best potential for a transient bout of fog and fluctuating visibilities LIFR to MVFR until 13z. Thereafter, predominantly VFR conditions are expected. Wildfire smoke will persist, but should remain aloft leading to hazy skies and not expecting impacts to surface based visibility. Tonight, we may see more river valley fog develop, but uncertainty exists with the fog potential and coverage. I have opted to introduce a period of MVFR visibility after 08z at DBQ, where confidence is a bit higher for at least some fog due to some potential for increased low level convergence ahead of a weak backdoor front south of Lake Michigan. Otherwise, winds will remain light during the period becoming predominantly NW/N today, then variable again tonight.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Heat Advisory from noon today to 8 PM CDT this evening for IAZ042-054. IL...Heat Advisory from noon today to 8 PM CDT this evening for ILZ001-002-007. MO...None.